Laminated glass

ABSTRACT

Provided is laminated glass capable of preventing occurrence of discoloration in the interlayer film in an end part of laminated glass, and keeping the appearance of laminated glass excellent. Laminated glass according to the present invention is laminate glass including a first lamination glass member, a second lamination glass member, and an interlayer film containing a thermoplastic resin, in which no discoloration occurs in the interlayer film irradiated with light in an end part of the laminated glass after a light irradiation test: “the laminated glass is irradiated with xenon light at a black panel temperature of 83° C., a temperature inside the vessel of 50° C. and a humidity of 50% RH for 2000 hours”, or discoloration occurs within a length of 1 mm or less inwardly from an end part of the interlayer film irradiated with light in the end part of the laminated glass after the light irradiation test.

TECHNICAL FIELD

The present invention relates to laminated glass having an interlayerfilm containing a thermoplastic resin.

BACKGROUND ART

Since laminated glass generates only a small amount of scattering glassfragments even when subjected to external impact and broken, thelaminated glass is excellent in safety. As such, the laminated glass iswidely used for automobiles, railway vehicles, aircraft, ships,buildings and the like. The laminated glass is produced by sandwichingan interlayer film between a pair of glass plates.

As one example of the laminated glass, the following Patent Document 1discloses laminated glass having an interlayer film containing apolyvinyl acetal resin, an ultraviolet absorber, a plasticizer, anadhesive force regulator, and an oxidation inhibitor. The ultravioletabsorber used in the interlayer film is a malonic ester compound and/oran oxanilide compound.

The following Patent Document 2 discloses laminated glass having aninterlayer film having low yellowing tendency, high transmittance toUV-A rays and visible light, and low transmittance to UV-B rays. Theinterlayer film contains a polyvinyl acetal, a plasticizer, and anoxanilide type compound which is an UV absorber.

RELATED ART DOCUMENT Patent Document

Patent Document 1: JP 2003-327454 A

Patent Document 2: US 2012/0052310 A1

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In conventional laminated glass, discoloration can occur in aninterlayer film in an end part of the laminated glass. In particular,discoloration to yellow is easy to occur in an end part of laminatedglass. This discoloration is likely to occur particularly when light,heat and the like is applied to the laminated glass.

When discoloration occurs in the interlayer film in an end part of thelaminated glass, the appearance of the laminated glass is impaired. Whenthe interlayer film is multi-layered, the discoloration is likely to beoccurred due to the layer being in contact with the glass plate of theinterlayer film.

While it is conceivable that the above problem is solved by increasingthe adding amount of the ultraviolet absorber in a conventionalinterlayer film, laminated glass prepared with such an interlayer filmcan have reduced transparency.

An object of the present invention is to provide laminated glass capableof preventing occurrence of discoloration in the interlayer film in anend part of laminated glass, and keeping the appearance of laminatedglass excellent.

Means for Solving the Problems

According to a broad aspect of the present invention, there is providedlaminated glass including a first lamination glass member, a secondlamination glass member, and an interlayer film containing athermoplastic resin, the interlayer film being arranged between thefirst lamination glass member and the second lamination glass member, inwhich no discoloration occurs in the interlayer film irradiated withlight in an end part of the laminated glass after a later-describedlight irradiation test, or discoloration occurs within a length of 1 mmor less inwardly from an end part of the interlayer film irradiated withlight in the end part of the laminated glass after the later-describedlight irradiation test.

Light irradiation test: the obtained laminated glass is irradiated withxenon light at a black panel temperature of 83° C., a temperature insidethe vessel of 50° C. and a humidity of 50% RH for 2000 hours. Theirradiance at the time of irradiation with xenon light is 180 W/m², andthe wavelength for measuring irradiance is 300 to 400 nm, and the innerfilter is made of quartz, and the outer filter is made of quartz: #275(cutoff 275 nm). When the first lamination glass member and the secondlamination glass member have the same visible light transmittance, thexenon light is irradiated from the first lamination glass member side.When the first lamination glass member and the second lamination glassmember are different in visible light transmittance, the xenon light isirradiated from the side of the lamination glass member having a highervisible light transmittance.

In a specific aspect of the laminated glass according to the presentinvention, the thermoplastic resin includes a polyvinyl acetal resin.

In a specific aspect of the laminated glass according to the presentinvention, a ratio of a content of the hydroxyl group of the polyvinylacetal resin in a layer of the interlayer film being in contact with thelamination glass member at a position of 2 mm inwardly from an end partof the laminated glass after the light irradiation test, to a content ofthe hydroxyl group of the polyvinyl acetal resin in a layer of theinterlayer film being in contact with the lamination glass member at aposition of 70 mm inwardly from an end part of the laminated glass afterthe light irradiation test is 1.2 or less.

In a specific aspect of the laminated glass according to the presentinvention, a content of the hydroxyl group of the polyvinyl acetal resinin the layer of the interlayer film being in contact with the laminationglass member at a position of 2 mm inwardly from an end part of thelaminated glass after the light irradiation test is 30% by mole or less.

In a specific aspect of the laminated glass according to the presentinvention, the polyvinyl acetal resin is polyvinyl butyral resin.

In a specific aspect of the laminated glass according to the presentinvention, there is a portion where a lateral surface of the interlayerfilm is exposed in an end part of the laminated glass.

In a specific aspect of the laminated glass according to the presentinvention, the interlayer film has a layer having a glass transitiontemperature of 10° C. or less and containing a thermoplastic resin, or alayer that is colored and contains a thermoplastic resin.

In a specific aspect of the laminated glass according to the presentinvention, the interlayer film includes a first layer containing athermoplastic resin, and a second layer containing a thermoplasticresin, and the second layer is arranged on a first surface side of thefirst layer.

In a specific aspect of the laminated glass according to the presentinvention, the interlayer film includes a third layer containing athermoplastic resin, and the third layer is arranged on a second surfaceside opposite to the first surface side of the first layer.

In a specific aspect of the laminated glass according to the presentinvention, the interlayer film has a visible light transmittance of 70%or more.

In a specific aspect of the laminated glass according to the presentinvention, the laminated glass is laminated glass that is to be used asglass for windshield in an automobile, and black coating is not appliedon the contact surface between the interlayer film and a laminationglass member on an outer side of the automobile.

In a specific aspect of the laminated glass according to the presentinvention, the laminated glass is used as side glass, roof glass orglass for backlight in automobiles.

Effect of the Invention

Laminated glass according to the present invention includes a firstlamination glass member, a second lamination glass member, and aninterlayer film containing a thermoplastic resin, and the interlayerfilm is arranged between the first lamination glass member and thesecond lamination glass member. In the laminated glass according to thepresent invention, no discoloration occurs in the interlayer filmirradiated with light in an end part of the laminated glass after thelight irradiation test, or discoloration occurs within a length of 1 mmor less inwardly from an end part of the interlayer film irradiated withlight in the end part of the laminated glass after the light irradiationtest. Since the laminated glass according to the present invention hasthe above configuration, it is possible to prevent occurrence ofdiscoloration in the interlayer film in an end part of the laminatedglass according to the present invention, and it is possible to keep theappearance of the laminated glass excellent.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view schematically showing laminated glass inaccordance with a first embodiment of the present invention.

FIG. 2 is a sectional view schematically showing laminated glass inaccordance with a second embodiment of the present invention.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

Laminated glass according to the present invention includes a firstlamination glass member, second lamination glass member and aninterlayer film. The interlayer film is arranged between the firstlamination glass member and the second lamination glass member. In thelaminated glass according to the present invention, the interlayer filmcontains a thermoplastic resin.

In the laminated glass according to the present invention, when thelater-described light irradiation test is conducted, no discolorationoccurs in the interlayer film irradiated with light in an end part ofthe laminated glass, or discoloration occurs within a length of 1 mm orless inwardly from an end part of the interlayer film irradiated withlight in the end part of the laminated glass. In the present invention,it is preferred that no discoloration occurs in an end part of theinterlayer film in the later-described light irradiation test. In thepresent invention, discoloration may occur in the interlayer film in thelater-described light irradiation test. In the present invention, whendiscoloration occurs in an end part of the interlayer film, the lengthin which the discoloration occurs is small.

Light irradiation test: the obtained laminated glass is irradiated withxenon light at a black panel temperature of 83° C., a temperature insidethe vessel of 50° C. and a humidity of 50% RH for 2000 hours. Theirradiance at the time of irradiation with xenon light is 180 W/m², andthe wavelength for measuring irradiance is 300 to 400 nm, and the innerfilter is made of quartz, and the outer filter is made of quartz: #275(cutoff 275 nm). When the first lamination glass member and the secondlamination glass member have the same visible light transmittance, thexenon light is irradiated from the first lamination glass member side.When the first lamination glass member and the second lamination glassmember are different in visible light transmittance, the xenon light isirradiated from the side of the lamination glass member having a highervisible light transmittance.

In the present invention, since the above configuration is provided, itis possible to prevent occurrence of discoloration in the interlayerfilm in an end part of laminated glass, and it is possible to keep theappearance of laminated glass excellent. In the present invention, it ispossible to suppress deterioration in transparency of laminated glass.

The length in which discoloration occurs means the shortest length(linear length) from the innermost position in the interlayer film inthe part where discoloration occurs, to an end part of the interlayerfilm between the first lamination glass member and the second laminationglass member. The length in which discoloration occurs indicates thedepth in which discoloration occurs in the interlayer film. Whendiscoloration occurs in a plurality of sites, the shortest length ismeasured for each of the plurality of discoloration sites, and themaximum value of the shortest length is regarded as a length in whichdiscoloration occurs.

The term “end part of laminated glass” means an end part of laminatedglass in the part where the first lamination glass member, theinterlayer film and the second lamination glass member are layered. Whenthere is a portion of the interlayer film that protrudes laterally fromthe part where the first lamination glass member, the interlayer film,and the second lamination glass member are layered, the inner side ofthe protruding portion of the interlayer film is the end part of thelaminated glass. When a covering portion that covers the interlayer filmis formed laterally of the part where the first lamination glass member,the interlayer film, and the second lamination glass member are layered,the inner side of the covering portion is the end part of the laminatedglass.

A content of the hydroxyl group of the polyvinyl acetal resin in thelayer of the interlayer film being in contact with the lamination glassmember of the interlayer film at a position of 2 mm inwardly from an endpart of the laminated glass after the light irradiation test is referredto as a content of the hydroxyl group at position of 2 mm. A content ofthe hydroxyl group of the polyvinyl acetal resin in the layer of theinterlayer film being in contact with the lamination glass member at aposition of 70 mm inwardly from an end part of the laminated glass afterthe light irradiation test is referred to as a content of the hydroxylgroup at position of 70 mm. A ratio of a content of the hydroxyl groupat a position of 2 mm to a content of the hydroxyl group at a positionof 70 mm (content of hydroxyl group at position of 2 mm/content ofhydroxyl group at position of 70 mm) is preferably 1.2 or less, morepreferably 1.15 or less, further preferably 1.1 or less. When the aboveratio (content of hydroxyl group at position of 2 mm/content of hydroxylgroup at position of 70 mm) is satisfied, it is possible to effectivelyprevent occurrence of discoloration in an end part of the laminatedglass, and keep the appearance of the laminated glass excellent.

When the interlayer film has a one-layer (first layer) structure, thelayer being in contact with the laminated glass is the interlayer film(first layer). When the interlayer film has a two-layer structureincluding a first layer and a second layer, the layer being in contactwith the laminated glass is the first layer and the second layer,namely, the first layer being in contact with the first lamination glassmember and the second layer being in contact with the second laminationglass member. When the interlayer film has a three-layer structureincluding a second layer, a first layer and a third layer, the layerbeing in contact with the laminated glass is the second layer and thethird layer, namely, the second layer being in contact with the firstlamination glass member and the third layer being in contact with thesecond lamination glass member.

From the viewpoint of effectively preventing occurrence of discolorationin an end part of the laminated glass, and keeping the appearance of thelaminated glass excellent, a content of the hydroxyl group of thepolyvinyl acetal resin in the layer of the interlayer film being incontact with the lamination glass member at a position of 2 mm inwardlyfrom an end part of the laminated glass after the light irradiation testis preferably 30% by mole or less.

In measuring the content of the hydroxyl group of the interlayer film ata position of 2 mm inwardly from an end part of the laminated glass, astrip of 1 mm wide centered on a line at 2 mm inwardly from an end partof the laminated glass is used. In measuring the content of the hydroxylgroup of the interlayer film at a position of 70 mm inwardly from an endpart of the laminated glass, a strip of 1 mm wide centered on a line at70 mm inwardly from an end part of the laminated glass is used.

In an end part of the laminated glass, there may be a portion in whichthe lateral surface of the interlayer film is exposed. Even when thelateral surface of the interlayer film is exposed, it is possible toprevent occurrence of discoloration in an end part of laminated glass,and it is possible to keep the appearance of laminated glass excellentin the present invention. In an end part of the laminated glass, theremay be a portion in which the lateral surface of the interlayer film isnot exposed.

It is preferred that the interlayer film have a layer having a glasstransition temperature of 10° C. or less and containing a thermoplasticresin, or a layer that is colored and contains a thermoplastic resin,and it is more preferred that the interlayer film have a layer having aglass transition temperature of 10° C. or less and containing athermoplastic resin. Although discoloration tends to be easy to occur inthese layers, it is possible to make discoloration difficult to occur,prevent occurrence of discoloration in an end part of the laminatedglass, and keep the appearance of the laminated glass excellent bysatisfying the configuration of the present invention, for example, byselection of a thermoplastic resin or control of the condition of theend part of the interlayer film.

The glass transition temperature is measured in the following manner.

The interlayer film obtained is stored for 1 month or more at atemperature of 23° C. and a humidity of 30%, after which, when theinterlayer film is a multi-layered interlayer film, each of the firstlayer and the third layer is peeled off to be isolated and press-moldedwith a press molding machine to obtain an object to be measured. Withregard to the object to be measured, the measurement is performed usingthe “ARES-G2” available from TA Instruments Japan Inc. In thisconnection, when the interlayer film is a single-layered interlayerfilm, the interlayer film is cut so as to have a diameter of 8 mm to bemeasured. A parallel plate with a diameter of 8 mm is used as a jig, andthe measurement is performed under the condition in which thetemperature is decreased from 100° C. to −10° C. at a temperaturedecreasing rate of 3° C./minute and under the condition of a frequencyof 1 Hz and a strain of 1%. In the measurement results obtained, thepeak temperature of the loss tangent is defined as the glass transitiontemperature Tg (° C.).

The colored layer contains, for example, a coloring agent. The visiblelight transmittance of the colored layer is, for example, 80% or less,and may be less than 70%.

From the viewpoint of enhancing the transparency of the laminated glass,the visible light transmittance of the interlayer film is preferably 70%or more, more preferably 80% or more, further preferably 90% or more.

The visible light transmittance is measured at a wavelength ranging from380 to 780 nm by using a spectrophotometer (“U-4100” available fromHitachi High-Tech Science Corporation) in conformity with JISR3211:1998. The visible light transmittance of the interlayer film maybe measured while the interlayer film is arranged between two sheets ofclear glass.

Hereinafter, specific embodiments of the present invention will bedescribed with reference to the drawings.

FIG. 1 is a sectional view schematically showing laminated glass inaccordance with a first embodiment of the present invention.

A laminated glass 11 shown in FIG. 1 includes a first lamination glassmember 21, a second lamination glass member 22 and an interlayer film 1.The interlayer film 1 is arranged between the first lamination glassmember 21 and the second lamination glass member 22, to be sandwichedtherebetween.

The first lamination glass member 21 is layered on a first surface 1 aof the interlayer film 1. The second lamination glass member 22 islayered on a second surface 1 b opposite to the first surface 1 a of theinterlayer film 1. The first lamination glass member 21 is layered on anouter surface 3 a of a second layer 3 of the interlayer film 1. Thesecond lamination glass member 22 is layered on an outer surface 4 a ofthe third layer 4 of the interlayer film 1.

The interlayer film 1 is a multi-layered interlayer film having a two ormore-layer structure. The interlayer film 1 includes a first layer 2,the second layer 3 arranged on a first surface 2 a side of the firstlayer 2, and a third layer 4 arranged on a second surface 2 b sideopposite to the first surface 2 a of the first layer 2. The second layer3 is layered on the first surface 2 a of the first layer 2. The thirdlayer 4 is layered on the second surface 2 b of the first layer 2. Thefirst layer 2 is an intermediate layer. Each of the second layer 3 andthe third layer 4 is, for example, a protective layer and is a surfacelayer in the present embodiment. The first layer 2 is arranged betweenthe second layer 3 and the third layer 4 to be sandwiched therebetween.Accordingly, the interlayer film 1 has a multilayer structure in whichthe second layer 3, the first layer 2, and the third layer 4 arearranged in this order. In the interlayer film 1, the second layer 3,the first layer 2, and the third layer 4 are arranged and layered inthis order.

It is preferred that the outer surface 3 a on the opposite side of thefirst layer 2 side of the second layer 3 be a surface on which alamination glass member is laminated. It is preferred that the outersurface 4 a on the opposite side of the first layer 2 side of the thirdlayer 4 be a surface on which a lamination glass member is laminated.

In this connection, other layers may be arranged between the first layer2 and the second layer 3 and between the first layer 2 and the thirdlayer 4, respectively. It is preferred that the first layer 2 and thesecond layer 3, and the first layer 2 and the third layer 4 be directlylayered. Examples of the other layer include layers containing athermoplastic resin such as a polyvinyl acetal resin, and layerscontaining, for example, polyethylene terephthalate.

The interlayer film 1 contains a thermoplastic resin. The first layer 2contains a thermoplastic resin. The second layer 3 contains athermoplastic resin. The third layer 4 contains a thermoplastic resin.

FIG. 2 is a sectional view schematically showing laminated glass inaccordance with a second embodiment of the present invention.

Laminated glass 41 shown in FIG. 2 includes the first lamination glassmember 21, the second lamination glass member 22 and an interlayer film31. The interlayer film 31 is arranged between the first laminationglass member 21 and the second lamination glass member 22, to besandwiched therebetween. The first lamination glass member 21 is layeredon a first surface 31 a of the interlayer film 31. The second laminationglass member 22 is layered on a second surface 31 b opposite to thefirst surface 31 a of the interlayer film 31.

The interlayer film 31 is a single-layered interlayer film having aone-layer structure. The interlayer film 31 is a first layer. Theinterlayer film 31 contains a thermoplastic resin.

The interlayer film has a one-layer structure or a two or more-layerstructure. The interlayer film may have a one-layer structure and mayhave a two or more-layer structure. The interlayer film may have atwo-layer structure and may have a three or more-layer structure. Theinterlayer may be an interlayer film having a one-layer structureincluding only a first layer (single-layered interlayer film) and may bean interlayer film having two or more-layer structure including a firstlayer and other layer (multi-layered interlayer film).

Hereinafter, the details of the first layer (including a single-layeredinterlayer film), the second layer, and the third layer which constitutethe interlayer film, and the details of each ingredient contained in thefirst layer, the second layer, and the third layer will be described.

(Thermoplastic Resin)

The interlayer film contains a thermoplastic resin (hereinafter,sometimes described as a thermoplastic resin (0)). It is preferred thatthe interlayer film contain a polyvinyl acetal resin (hereinafter,sometimes described as a polyvinyl acetal resin (0)) as thethermoplastic resin (0). It is preferred that the first layer contain athermoplastic resin (hereinafter, sometimes described as a thermoplasticresin (1)). It is preferred that the first layer contain a polyvinylacetal resin (hereinafter, sometimes described as a polyvinyl acetalresin (1)) as the thermoplastic resin (1). It is preferred that thesecond layer contain a thermoplastic resin (hereinafter, sometimesdescribed as a thermoplastic resin (2)). It is preferred that the secondlayer contain a polyvinyl acetal resin (hereinafter, sometimes describedas a polyvinyl acetal resin (2)) as the thermoplastic resin (2). It ispreferred that the third layer contain a thermoplastic resin(hereinafter, sometimes described as a thermoplastic resin (3)). It ispreferred that the third layer contain a polyvinyl acetal resin(hereinafter, sometimes described as a polyvinyl acetal resin (3)) asthe thermoplastic resin (3). The thermoplastic resin (1), thethermoplastic resin (2), and the thermoplastic resin (3) may be the sameor different from one another. For still higher sound insulatingproperties, it is preferred that the thermoplastic resin (1) bedifferent from the thermoplastic resin (2) and the thermoplastic resin(3). Each of the polyvinyl acetal resin (1), the polyvinyl acetal resin(2) and the polyvinyl acetal resin (3) may be the same or different fromone another. For still higher sound insulating properties, it ispreferred that the polyvinyl acetal resin (1) be different from thepolyvinyl acetal resin (2) and the polyvinyl acetal resin (3). One kindof each of the thermoplastic resin (0), the thermoplastic resin (1), thethermoplastic resin (2), and the thermoplastic resin (3) may be usedalone and two or more kinds thereof may be used in combination. One kindof each of the polyvinyl acetal resin (0), the polyvinyl acetal resin(1), the polyvinyl acetal resin (2), and the polyvinyl acetal resin (3)may be used alone and two or more kinds thereof may be used incombination.

Examples of the thermoplastic resin include a polyvinyl acetal resin, anethylene-vinyl acetate copolymer resin, an ethylene-acrylic acidcopolymer resin, a polyurethane resin, an ionomer resin, a polyvinylalcohol resin, and a cycloolefin resin. Thermoplastic resins other thanthese may be used.

For example, the polyvinyl acetal resin can be produced by acetalizingpolyvinyl alcohol (PVA) with an aldehyde. It is preferred that thepolyvinyl acetal resin be an acetalized product of polyvinyl alcohol.For example, the polyvinyl alcohol can be obtained by saponifyingpolyvinyl acetate. The saponification degree of the polyvinyl alcoholgenerally lies within the range of 70 to 99.9% by mole.

From the viewpoint of effectively preventing occurrence of discolorationin an end part of laminated glass, and keeping the appearance oflaminated glass excellent, it is preferred that the interlayer filmcontain a polyvinyl butyral resin or an ionomer resin. From theviewpoint of effectively preventing occurrence of discoloration in anend part of laminated glass, and keeping the appearance of laminatedglass excellent, it is preferred that the polyvinyl acetal resin be apolyvinyl butyral resin. From the viewpoint of effectively preventingoccurrence of discoloration in an end part of laminated glass, andkeeping the appearance of laminated glass excellent, it is preferredthat the ionomer resin be a polyvinyl acetal ionomer resin.

The polyvinyl acetal ionomer resin is an ionomerized polyvinyl acetalresin. It is preferred that the polyvinyl acetal ionomer resin containpolyvinyl acetal into which an acid group is introduced.

The polyvinyl acetal ionomer resin has, for example, a —CH₂—CH— group ina main chain. The polyvinyl acetal ionomer resin has a polyvinyl acetalskeleton. The polyvinyl acetal skeleton has a —CH₂—CH— group in a mainchain. To the carbon atom in the “—CH—” moiety in a —CH₂—CH— group,another group is bound. In the polyvinyl acetal ionomer resin, it ispreferred that —CH₂—CH— groups be consecutive in the main chain.

For neutralization in obtaining the polyvinyl acetal ionomer resin,metal is used. From the viewpoint of effectively enhancing the shockresistance at low temperature and the self-repairability, the metal ispreferably Na, Li, K, Mg, Zn, Cu, Co, Al, Fe, Ni, Cr or Mn. It ispreferred that the metal contain, in particular, Na.

Examples of the method for producing the polyvinyl acetal ionomer resininclude the following method. Method of copolymerizing polyvinyl acetateand a monomer having a group capable of becoming an ionic functionalgroup, saponifying, and acetalizing with aldehyde, followed byionomerization. Method of acetalizing polyvinyl alcohol (PVA) with analdehyde having a group capable of becoming an ionic functional group,followed by ionomerization. Method of acetalizing polyvinyl acetal withan aldehyde having a group capable of becoming an ionic functionalgroup, followed by ionomerization.

Examples of the method for ionomerization include a method of adding ametal-containing compound into a solution, and a method of adding ametal-containing compound during kneading. The metal-containing compoundmay be added in a state of a solution.

It is preferred that the ionic functional group be a carboxyl group, abase of carboxyl group, a sulfonic acid group, a base of sulfonic acidgroup, a sulfinic acid group, a base of sulfinic acid group, a sulfenicacid group, a base of sulfenic acid group, a phosphoric acid group, abase of phosphoric acid group, a phosphonic acid group, a base ofphosphonic acid group, an amino group, or a base of amino group.Regarding these groups, the effect of ionomerization effectivelyappears, and the effect of the present invention effectively appears.

The content of the ionic functional group means a sum of a percentage ofthe group that can become an ionic functional group in the resin, and apercentage of the ionic functional group constituting the metal salt ofthe ionic functional group. The content of the ionic functional groupcan be determined by using NMR or the like. For example, the content ofthe ionic functional group can be calculated from an integrated value ofthe peak originated from the ionic functional group (appearing around 45ppm in the carboxyl group) and the peak originated from the main chainappearing around 30 ppm in carbon NMR.

The average polymerization degree of the polyvinyl alcohol (PVA) ispreferably 200 or more, more preferably 500 or more, even morepreferably 1500 or more, further preferably 1600 or more, especiallypreferably 2600 or more, most preferably 2700 or more, preferably 5000or less, more preferably 4000 or less and further preferably 3500 orless. When the average polymerization degree is the above lower limit ormore, the penetration resistance of laminated glass is further enhanced.When the average polymerization degree is the above upper limit or less,formation of an interlayer film is facilitated.

The average polymerization degree of the polyvinyl alcohol is determinedby a method in accordance with JIS K6726 “Testing methods for polyvinylalcohol”.

The number of carbon atoms of the acetal group contained in thepolyvinyl acetal resin is not particularly limited. The aldehyde used atthe time of producing the polyvinyl acetal resin is not particularlylimited. It is preferred that the number of carbon atoms of the acetalgroup in the polyvinyl acetal resin fall within the range of 3 to 5 andit is more preferred that the number of carbon atoms of the acetal groupbe 3 or 4. When the number of carbon atoms of the acetal group in thepolyvinyl acetal resin is 3 or more, the glass transition temperature ofthe interlayer film is sufficiently lowered.

The aldehyde is not particularly limited. In general, an aldehyde with 1to 10 carbon atoms is preferably used. Examples of the aldehyde with 1to 10 carbon atoms include formaldehyde, acetaldehyde, propionaldehyde,n-butyraldehyde, isobutyraldehyde, n-valeraldehyde,2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde,n-decylaldehyde, benzaldehyde, and the like. Propionaldehyde,n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, or n-valeraldehydeis preferred, propionaldehyde, n-butyraldehyde, or isobutyraldehyde ismore preferred, and n-butyraldehyde is further preferred. One kind ofthe aldehyde may be used alone, and two or more kinds thereof may beused in combination.

The content of the hydroxyl group (the amount of hydroxyl groups) of thepolyvinyl acetal resin (0) is preferably 15% by mole or more and morepreferably 18% by mole or more and is preferably 40% by mole or less andmore preferably 35% by mole or less. When the content of the hydroxylgroup is the above lower limit or more, the adhesive force of theinterlayer film is further enhanced. Moreover, when the content of thehydroxyl group is the above upper limit or less, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated.

A content of the hydroxyl group (the amount of hydroxyl groups) of thepolyvinyl acetal resin (1) is preferably 17% by mole or more, morepreferably 20% by mole or more, further preferably 22% by mole or moreand is preferably 28% by mole or less, more preferably 27% by mole orless, further preferably 25% by mole or less, especially preferably 24%by mole or less. When the content of the hydroxyl group is the abovelower limit or more, the mechanical strength of the interlayer film isfurther enhanced. In particular, when the content of the hydroxyl groupof the polyvinyl acetal resin (1) is 20% by mole or more, the resin ishigh in reaction efficiency and is excellent in productivity, andmoreover, when being 28% by mole or less, the sound insulating propertyof laminated glass is further enhanced. Moreover, when the content ofthe hydroxyl group is the above upper limit or less, the flexibility ofthe interlayer film is enhanced and the handling of the interlayer filmis facilitated.

Each of the contents of the hydroxyl group of the polyvinyl acetal resin(2) and the polyvinyl acetal resin (3) is preferably 25% by mole ormore, more preferably 28% by mole or more, more preferably 30% by moleor more, still more preferably 31.5% by mole or more, further preferably32% by mole or more, especially preferably 33% by mole or more. Each ofthe contents of the hydroxyl group of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) is preferably 38% by mole or less, morepreferably 37% by mole or less, further preferably 36.5% by mole orless, especially preferably 36% by mole or less. When the content of thehydroxyl group is the above lower limit or more, the adhesive force ofthe interlayer film is further enhanced. Moreover, when the content ofthe hydroxyl group is the above upper limit or less, the flexibility ofthe interlayer film is enhanced and the handling of the interlayer filmis facilitated.

From the viewpoint of further enhancing the sound insulating properties,it is preferred that the content of the hydroxyl group of the polyvinylacetal resin (1) be lower than the content of the hydroxyl group of thepolyvinyl acetal resin (2). From the viewpoint of further enhancing thesound insulating properties, it is preferred that the content of thehydroxyl group of the polyvinyl acetal resin (1) be lower than thecontent of the hydroxyl group of the polyvinyl acetal resin (3). Fromthe viewpoint of still further enhancing the sound insulatingproperties, the absolute value of a difference between the content ofthe hydroxyl group of the polyvinyl acetal resin (1) and the content ofthe hydroxyl group of the polyvinyl acetal resin (2) is preferably 1% bymole or more, more preferably 5% by mole or more, further preferably 9%by mole or more, especially preferably 10% by mole or more, mostpreferably 12% by mole or more. From the viewpoint of still furtherenhancing the sound insulating properties, the absolute value of adifference between the content of the hydroxyl group of the polyvinylacetal resin (1) and the content of the hydroxyl group of the polyvinylacetal resin (3) is preferably 1% by mole or more, more preferably 5% bymole or more, further preferably 9% by mole or more, especiallypreferably 10% by mole or more, most preferably 12% by mole or more. Anabsolute value of difference between the content of the hydroxyl groupof the polyvinyl acetal resin (1) and the content of the hydroxyl groupof the polyvinyl acetal resin (2) is preferably 20% by mole or less. Anabsolute value of difference between the content of the hydroxyl groupof the polyvinyl acetal resin (1) and the content of the hydroxyl groupof the polyvinyl acetal resin (3) is preferably 20% by mole or less.

The content of the hydroxyl group of the polyvinyl acetal resin is amole fraction, represented in percentage, obtained by dividing theamount of ethylene groups to which the hydroxyl group is bonded by thetotal amount of ethylene groups in the main chain. For example, theamount of ethylene groups to which the hydroxyl group is bonded can bedetermined in accordance with JIS K6728 “Testing methods for polyvinylbutyral”.

The acetylation degree (the amount of acetyl groups) of the polyvinylacetal resin (0) is preferably 0.1% by mole or more, more preferably0.3% by mole or more, further preferably 0.5% by mole or more and ispreferably 30% by mole or less, more preferably 25% by mole or less, andfurther preferably 20% by mole or less. When the acetylation degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetylation degreeis the above upper limit or less, with regard to the interlayer film andlaminated glass, the moisture resistance thereof is enhanced.

The acetylation degree (the amount of acetyl groups) of the polyvinylacetal resin (1) is preferably 0.01% by mole or more, more preferably0.1% by mole or more, even more preferably 7% by mole or more, furtherpreferably 9% by mole or more and is preferably 30% by mole or less,more preferably 25% by mole or less, further preferably 24% by mole orless, especially preferably 20% by mole or less. When the acetylationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetylation degree is the above upper limit or less, with regard to theinterlayer film and laminated glass, the moisture resistance thereof isenhanced. In particular, when the acetylation degree of the polyvinylacetal resin (1) is 0.1% by mole or more and is 25% by mole or less, theresulting laminated glass is excellent in penetration resistance.

The acetylation degree of each of the polyvinyl acetal resin (2) and thepolyvinyl acetal resin (3) is preferably 0.01% by mole or more, and morepreferably 0.5% by mole or more and is preferably 10% by mole or less,and more preferably 2% by mole or less. When the acetylation degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetylation degreeis the above upper limit or less, with regard to the interlayer film andlaminated glass, the moisture resistance thereof is enhanced.

The acetylation degree is a mole fraction, represented in percentage,obtained by dividing the amount of ethylene groups to which the acetylgroup is bonded by the total amount of ethylene groups in the mainchain. For example, the amount of ethylene groups to which the acetylgroup is bonded can be determined in accordance with JIS K6728 “Testingmethods for polyvinyl butyral”.

The acetalization degree of the polyvinyl acetal resin (0) (thebutyralization degree in the case of a polyvinyl butyral resin) ispreferably 60% by mole or more, more preferably 63% by mole or more andis preferably 85% by mole or less, more preferably 75% by mole or less,and further preferably 70% by mole or less. When the acetalizationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetalization degree is the above upper limit or less, the reaction timerequired for producing the polyvinyl acetal resin is shortened.

The acetalization degree of the polyvinyl acetal resin (1) (thebutyralization degree in the case of a polyvinyl butyral resin) ispreferably 47% by mole or more and more preferably 60% by mole or moreand is preferably 85% by mole or less, more preferably 80% by mole orless, further preferably 75% by mole or less. When the acetalizationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetalization degree is the above upper limit or less, the reaction timerequired for producing the polyvinyl acetal resin is shortened.

The acetalization degree of each of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) (the butyralization degree in the case ofa polyvinyl butyral resin) is preferably 55% by mole or more, and morepreferably 60% by mole or more and is preferably 75% by mole or less,and more preferably 71% by mole or less. When the acetalization degreeis the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetalization degree is the above upper limit or less, the reaction timerequired for producing the polyvinyl acetal resin is shortened.

The acetalization degree is determined in the following manner. From thetotal amount of the ethylene group in the main chain, the amount of theethylene group to which the hydroxyl group is bonded and the amount ofthe ethylene group to which the acetyl group is bonded are subtracted.The obtained value is divided by the total amount of the ethylene groupin the main chain to obtain a mole fraction. The mole fractionrepresented in percentage is the acetalization degree.

In this connection, it is preferred that the content of the hydroxylgroup (the amount of hydroxyl groups), the acetalization degree (thebutyralization degree) and the acetylation degree be calculated from theresults determined by a method in accordance with JIS K6728 “Testingmethods for polyvinyl butyral”. In this context, a method in accordancewith ASTM D1396-92 may be used. When the polyvinyl acetal resin is apolyvinyl butyral resin, the content of the hydroxyl group (the amountof hydroxyl groups), the acetalization degree (the butyralizationdegree) and the acetylation degree can be calculated from the resultsmeasured by a method in accordance with JIS K6728 “Testing methods forpolyvinyl butyral”.

(Plasticizer)

From the viewpoint of further enhancing the adhesive force of aninterlayer film, it is preferred that the interlayer film according tothe present invention contain a plasticizer (hereinafter, sometimesdescribed as a plasticizer (0)). It is preferred that the first layercontain a plasticizer (hereinafter, sometimes described as a plasticizer(1)). It is preferred that the second layer contain a plasticizer(hereinafter, sometimes described as a plasticizer (2)). It is preferredthat the third layer contain a plasticizer (hereinafter, sometimesdescribed as a plasticizer (3)). When the thermoplastic resin containedin the interlayer film is a polyvinyl acetal resin, it is especiallypreferred that the interlayer film (the respective layers) contain aplasticizer. It is preferred that a layer containing a polyvinyl acetalresin contain a plasticizer.

The plasticizer is not particularly limited. As the plasticizer, aconventionally known plasticizer can be used. One kind of theplasticizer may be used alone and two or more kinds thereof may be usedin combination.

Examples of the plasticizer include organic ester plasticizers such as amonobasic organic acid ester and a polybasic organic acid ester, organicphosphate plasticizers such as an organic phosphate plasticizer and anorganic phosphite plasticizer, and the like. Organic ester plasticizersare preferred. It is preferred that the plasticizer be a liquidplasticizer.

Examples of the monobasic organic acid ester include a glycol esterobtained by the reaction of a glycol with a monobasic organic acid, andthe like. Examples of the glycol include triethylene glycol,tetraethylene glycol, tripropylene glycol, and the like. Examples of themonobasic organic acid include butyric acid, isobutyric acid, caproicacid, 2-ethylbutyric acid, heptanoic acid, n-octylic acid,2-ethylhexanoic acid, n-nonylic acid, decanoic acid, and the like.

Examples of the polybasic organic acid ester include an ester compoundof a polybasic organic acid and an alcohol having a linear or branchedstructure of 4 to 8 carbon atoms. Examples of the polybasic organic acidinclude adipic acid, sebacic acid, azelaic acid, and the like.

Examples of the organic ester plasticizer include triethylene glycoldi-2-ethylpropanoate, triethylene glycol di-2-ethylbutyrate, triethyleneglycol di-2-ethylhexanoate, triethylene glycol dicaprylate, triethyleneglycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethyleneglycol di-n-heptanoate, dibutyl sebacate, dioctyl azelate, dibutylcarbitol adipate, ethylene glycol di-2-ethylbutyrate, 1,3-propyleneglycol di-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate,diethylene glycol di-2-ethylbutyrate, diethylene glycoldi-2-ethylhexanoate, dipropylene glycol di-2-ethylbutyrate, triethyleneglycol di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate,diethylene glycol dicaprylate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, a mixture of heptyl adipate and nonyl adipate,diisononyl adipate, diisodecyl adipate, heptyl nonyl adipate, dibutylsebacate, oil-modified sebacic alkyds, a mixture of a phosphoric acidester and an adipic acid ester, and the like. Organic ester plasticizersother than these may be used. Other adipic acid esters other than theabove-described adipic acid esters may be used.

Examples of the organic phosphate plasticizer include tributoxyethylphosphate, isodecyl phenyl phosphate, triisopropyl phosphate, and thelike.

It is preferred that the plasticizer be a diester plasticizerrepresented by the following formula (1).

In the foregoing formula (1), R1 and R2 each represent an organic groupwith 5 to 10 carbon atoms, R3 represents an ethylene group, anisopropylene group, or an n-propylene group, and p represents an integerof 3 to 10. It is preferred that R1 and R2 in the foregoing formula (1)each be an organic group with 6 to 10 carbon atoms.

It is preferred that the plasticizer include triethylene glycoldi-2-ethylhexanoate (3GO) or triethylene glycol di-2-ethylbutyrate (3GH)and it is more preferred that the plasticizer include triethylene glycoldi-2-ethylhexanoate.

In the interlayer film, the content of the plasticizer (0) relative to100 parts by weight of the thermoplastic resin (0) is referred to ascontent (0). The content (0) is preferably 5 parts by weight or more,more preferably 25 parts by weight or more, further preferably 30 partsby weight or more, and is preferably 100 parts by weight or less, morepreferably 60 parts by weight or less, further preferably 50 parts byweight or less. When the content (0) is the above lower limit or more,the penetration resistance of laminated glass is further enhanced. Whenthe content (0) is the above upper limit or less, the transparency ofthe interlayer film is further enhanced.

In the first layer, the content of the plasticizer (1) relative to 100parts by weight of the thermoplastic resin (1) is referred to as content(1). The content (1) is preferably 50 parts by weight or more, morepreferably 55 parts by weight or more, further preferably 60 parts byweight or more, and is preferably 100 parts by weight or less, morepreferably 90 parts by weight or less, further preferably 85 parts byweight or less, especially preferably 80 parts by weight or less. Whenthe content (1) is the above lower limit or more, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated. When the content (1) is the above upper limit or less, thepenetration resistance of laminated glass is further enhanced.

In the second layer, the content of the plasticizer (2) relative to 100parts by weight of the thermoplastic resin (2) is referred to as content(2). In the third layer, the content of the plasticizer (3) relative to100 parts by weight of the thermoplastic resin (3) is referred to ascontent (3). Each of the content (2) and the content (3) is preferably 5parts by weight or more, more preferably 10 parts by weight or more,still more preferably 15 parts by weight or more, further preferably 20parts by weight or more, especially preferably 24 parts by weight ormore, and most preferably 25 parts by weight or more. Each of thecontent (2) and the content (3) is preferably 45 parts by weight orless, more preferably 40 parts by weight or less, further preferably 35parts by weight or less, especially preferably 32 parts by weight orless, and most preferably 30 parts by weight or less. When the content(2) and the content (3) are the above lower limit or more, theflexibility of the interlayer film is enhanced and the handling of theinterlayer film is facilitated. When the content (2) and the content (3)are the above upper limit or less, the penetration resistance oflaminated glass is further enhanced.

For the purpose of enhancing the sound insulating properties oflaminated glass, it is preferred that the content (1) be larger than thecontent (2) and it is preferred that the content (1) be larger than thecontent (3).

From the viewpoint of further enhancing the sound insulating property oflaminated glass, each of the absolute value of difference between thecontent (2) and the content (1) and the absolute value of differencebetween the content (3) and the content (1) is preferably 10 parts byweight or more, more preferably 15 parts by weight or more, and furtherpreferably 20 parts by weight or more. Each of the absolute value ofdifference between the content (2) and the content (1) and the absolutevalue of difference between the content (3) and the content (1) ispreferably 80 parts by weight or less, more preferably 75 parts byweight or less, further preferably 70 parts by weight or less.

(Heat Shielding Substance)

It is preferred that the interlayer film contain a heat shieldingsubstance (heat shielding compound). It is preferred that the firstlayer contain a heat shielding substance. It is preferred that thesecond layer contain a heat shielding substance. It is preferred thatthe third layer contain a heat shielding substance. One kind of the heatshielding substance may be used alone, and two or more kinds thereof maybe used in combination.

It is preferred that the heat shielding substance contain at least onekind of Ingredient X among a phthalocyanine compound, a naphthalocyaninecompound, and an anthracyanine compound or contain heat shieldingparticles. In this case, the heat shielding compound may be constitutedof both of the Ingredient X and the heat shielding particles.

Ingredient X:

It is preferred that the interlayer film include at least one kind ofIngredient X among a phthalocyanine compound, a naphthalocyaninecompound, and an anthracyanine compound. It is preferred that the firstlayer contain the Ingredient X. It is preferred that the second layercontain the Ingredient X. It is preferred that the third layer containthe Ingredient X. The Ingredient X is a heat shielding substance. Onekind of the Ingredient X may be used alone, and two or more kindsthereof may be used in combination.

The Ingredient X is not particularly limited. As the Ingredient X,conventionally known phthalocyanine compound, naphthalocyanine compoundand anthracyanine compound can be used.

Examples of the Ingredient X include phthalocyanine, a derivative ofphthalocyanine, naphthalocyanine, a derivative of naphthalocyanine,anthracyanine, and a derivative of anthracyanine, and the like. It ispreferred that each of the phthalocyanine compound and the derivative ofphthalocyanine have a phthalocyanine skeleton. It is preferred that eachof the naphthalocyanine compound and the derivative of naphthalocyaninehave a naphthalocyanine skeleton. It is preferred that each of theanthracyanine compound and the derivative of anthracyanine have ananthracyanine skeleton.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof, itis preferred that the Ingredient X be at least one kind selected fromthe group consisting of phthalocyanine, a derivative of phthalocyanine,naphthalocyanine and a derivative of naphthalocyanine, and it is morepreferred that the Ingredient X be at least one kind amongphthalocyanine and a derivative of phthalocyanine.

From the viewpoints of effectively enhancing the heat shieldingproperties and maintaining the visible light transmittance at a higherlevel over a long period of time, it is preferred that the Ingredient Xcontain vanadium atoms or copper atoms. It is preferred that theIngredient X contain vanadium atoms and it is also preferred that theIngredient X contain copper atoms. It is more preferred that theIngredient X be at least one kind among phthalocyanine containingvanadium atoms or copper atoms and a derivative of phthalocyaninecontaining vanadium atoms or copper atoms. With regard to the interlayerfilm and laminated glass, from the viewpoint of still further enhancingthe heat shielding properties thereof, it is preferred that theIngredient X have a structural unit in which an oxygen atom is bonded toa vanadium atom.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the Ingredient X (a first layer, a second layer, or a thirdlayer), the content of the Ingredient X is preferably 0.001% by weightor more, more preferably 0.005% by weight or more, further preferably0.01% by weight or more, especially preferably 0.02% by weight or more.In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the Ingredient X (a first layer, a second layer, or a thirdlayer), the content of the Ingredient X is preferably 0.2% by weight orless, more preferably 0.1% by weight or less, further preferably 0.05%by weight or less, especially preferably 0.04% by weight or less. Whenthe content of the Ingredient X is the above lower limit or more and theabove upper limit or less, the heat shielding properties aresufficiently enhanced and the visible light transmittance issufficiently enhanced. For example, it is possible to make the visiblelight transmittance 70% or more.

Heat Shielding Particles:

It is preferred that the interlayer film contain heat shieldingparticles. It is preferred that the first layer contain the heatshielding particles. It is preferred that the second layer contain theheat shielding particles. It is preferred that the third layer containthe heat shielding particles. The heat shielding particle is of a heatshielding substance. By the use of heat shielding particles, infraredrays (heat rays) can be effectively cut off. One kind of the heatshielding particles may be used alone, and two or more kinds thereof maybe used in combination.

From the viewpoint of further enhancing the heat shielding properties oflaminated glass, it is more preferred that the heat shielding particlesbe metal oxide particles. It is preferred that the heat shieldingparticle be a particle (a metal oxide particle) formed from an oxide ofa metal.

The energy amount of an infrared ray with a wavelength of 780 nm orlonger which is longer than that of visible light is small as comparedwith an ultraviolet ray. However, the thermal action of infrared rays islarge, and when infrared rays are absorbed into a substance, heat isreleased from the substance. Accordingly, infrared rays are generallycalled heat rays. By the use of the heat shielding particles, infraredrays (heat rays) can be effectively cut off. In this connection, theheat shielding particle means a particle capable of absorbing infraredrays.

Specific examples of the heat shielding particles include metal oxideparticles such as aluminum-doped tin oxide particles, indium-doped tinoxide particles, antimony-doped tin oxide particles (ATO particles),gallium-doped zinc oxide particles (GZO particles), indium-doped zincoxide particles (IZO particles), aluminum-doped zinc oxide particles(AZO particles), niobium-doped titanium oxide particles, sodium-dopedtungsten oxide particles, cesium-doped tungsten oxide particles,thallium-doped tungsten oxide particles, rubidium-doped tungsten oxideparticles, tin-doped indium oxide particles (ITO particles), tin-dopedzinc oxide particles and silicon-doped zinc oxide particles, lanthanumhexaboride (LaB₆) particles, and the like. Heat shielding particlesother than these may be used. Since the heat ray shielding function ishigh, preferred are metal oxide particles, more preferred are ATOparticles, GZO particles, IZO particles, ITO particles or tungsten oxideparticles, and especially preferred are ITO particles or tungsten oxideparticles. In particular, since the heat ray shielding function is highand the particles are readily available, preferred are tin-doped indiumoxide particles (ITO particles), and also preferred are tungsten oxideparticles.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof, itis preferred that the tungsten oxide particles be metal-doped tungstenoxide particles. Examples of the “tungsten oxide particles” includemetal-doped tungsten oxide particles. Specifically, examples of themetal-doped tungsten oxide particles include sodium-doped tungsten oxideparticles, cesium-doped tungsten oxide particles, thallium-dopedtungsten oxide particles, rubidium-doped tungsten oxide particles, andthe like.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof,cesium-doped tungsten oxide particles are especially preferred. Withregard to the interlayer film and laminated glass, from the viewpoint ofstill further enhancing the heat shielding properties thereof, it ispreferred that the cesium-doped tungsten oxide particles be tungstenoxide particles represented by the formula: Cs_(0.33)WO₃.

The average particle diameter of the heat shielding particles ispreferably 0.01 μm or more, more preferably 0.02 μm or more, and ispreferably 0.1 μm or less, more preferably 0.05 μm or less. When theaverage particle diameter is the above lower limit or more, the heat rayshielding properties are sufficiently enhanced. When the averageparticle diameter is the above upper limit or less, the dispersibilityof heat shielding particles is enhanced.

The “average particle diameter” refers to the volume average particlediameter. The average particle diameter can be measured using a particlesize distribution measuring apparatus (“UPA-EX150” available fromNIKKISO CO., LTD.), or the like.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the heat shielding particles (a first layer, a second layer,or a third layer), each content of the heat shielding particles (inparticular, the content of tungsten oxide particles) is preferably 0.01%by weight or more, more preferably 0.1% by weight or more, furtherpreferably 1% by weight or more, especially preferably 1.5% by weight ormore. In 100% by weight of the interlayer film or in 100% by weight of alayer containing the heat shielding particles (a first layer, a secondlayer, or a third layer), each content of the heat shielding particles(in particular, the content of tungsten oxide particles) is preferably6% by weight or less, more preferably 5.5% by weight or less, furtherpreferably 4% by weight or less, especially preferably 3.5% by weight orless, most preferably 3% by weight or less. When the content of the heatshielding particles is the above lower limit or more and the above upperlimit or less, the heat shielding properties are sufficiently enhancedand the visible light transmittance is sufficiently enhanced.

(Metal Salt)

It is preferred that the interlayer film contain at least one kind ofmetal salt (hereinafter, sometimes described as Metal salt M) among analkali metal salt, an alkaline earth metal salt, and a magnesium salt.It is preferred that the first layer contain the Metal salt M. It ispreferred that the second layer contain the Metal salt M. It ispreferred that the third layer contain the Metal salt M. By the use ofthe Metal salt M, controlling the adhesivity between the interlayer filmand a lamination glass member such as a glass plate or the adhesivitybetween respective layers in the interlayer film is facilitated. Onekind of the Metal salt M may be used alone, and two or more kindsthereof may be used in combination.

It is preferred that the Metal salt M contain at least one kind of metalselected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr andBa. It is preferred that the metal salt included in the interlayer filmcontain at least one kind of metal among K and Mg.

Moreover, it is more preferred that the Metal salt M be an alkali metalsalt of an organic acid with 2 to 16 carbon atoms, an alkaline earthmetal salt of an organic acid with 2 to 16 carbon atoms, and a magnesiumsalt of an organic acid with 2 to 16 carbon atoms, and it is furtherpreferred that the Metal salt M be a magnesium carboxylate with 2 to 16carbon atoms or a potassium carboxylate with 2 to 16 carbon atoms.

Examples of the magnesium carboxylate with 2 to 16 carbon atoms and thepotassium carboxylate with 2 to 16 carbon atoms include magnesiumacetate, potassium acetate, magnesium propionate, potassium propionate,magnesium 2-ethylbutyrate, potassium 2-ethylbutanoate, magnesium2-ethylhexanoate, potassium 2-ethylhexanoate, and the like.

The total of the contents of Mg and K in an interlayer film containingthe Metal salt M or a layer containing the Metal salt M (a first layer,a second layer, or a third layer) is preferably 5 ppm or more, morepreferably 10 ppm or more, and further preferably 20 ppm or more and ispreferably 300 ppm or less, more preferably 250 ppm or less, and furtherpreferably 200 ppm or less. When the total of the contents of Mg and Kis the above lower limit or more and the above upper limit or less, theadhesivity between the interlayer film and a glass plate or theadhesivity between respective layers in the interlayer film can befurther well controlled.

(Ultraviolet Ray Screening Agent)

It is preferred that the interlayer film contain an ultraviolet rayscreening agent. It is preferred that the first layer contain anultraviolet ray screening agent. It is preferred that the second layercontain an ultraviolet ray screening agent. It is preferred that thethird layer contain an ultraviolet ray screening agent. By the use of anultraviolet ray screening agent, even when the interlayer film and thelaminated glass are used for a long period of time, the visible lighttransmittance becomes further hard to be lowered. One kind of theultraviolet ray screening agent may be used alone, and two or more kindsthereof may be used in combination.

Examples of the ultraviolet ray screening agent include an ultravioletray absorber. It is preferred that the ultraviolet ray screening agentbe an ultraviolet ray absorber.

Examples of the ultraviolet ray screening agent include an ultravioletray screening agent containing a metal atom, an ultraviolet rayscreening agent containing a metal oxide, an ultraviolet ray screeningagent having a benzotriazole structure (a benzotriazole compound), anultraviolet ray screening agent having a benzophenone structure (abenzophenone compound), an ultraviolet ray screening agent having atriazine structure (a triazine compound), an ultraviolet ray screeningagent having a malonic acid ester structure (a malonic acid estercompound), an ultraviolet ray screening agent having an oxanilidestructure (an oxanilide compound), an ultraviolet ray screening agenthaving a benzoate structure (a benzoate compound), and the like.

Examples of the ultraviolet ray screening agent containing a metal atominclude platinum particles, particles in which the surface of platinumparticles is coated with silica, palladium particles, particles in whichthe surface of palladium particles is coated with silica, and the like.It is preferred that the ultraviolet ray screening agent not be heatshielding particles.

The ultraviolet ray screening agent is preferably an ultraviolet rayscreening agent having a benzotriazole structure, an ultraviolet rayscreening agent having a benzophenone structure, an ultraviolet rayscreening agent having a triazine structure, or an ultraviolet rayscreening agent having a benzoate structure. The ultraviolet rayscreening agent is more preferably an ultraviolet ray screening agenthaving a benzotriazole structure or an ultraviolet ray screening agenthaving a benzophenone structure, and is further preferably anultraviolet ray screening agent having a benzotriazole structure.

Examples of the ultraviolet ray screening agent containing a metal oxideinclude zinc oxide, titanium oxide, cerium oxide, and the like.Furthermore, with regard to the ultraviolet ray screening agentcontaining a metal oxide, the surface thereof may be coated with anymaterial. Examples of the coating material for the surface of theultraviolet ray screening agent containing a metal oxide include aninsulating metal oxide, a hydrolyzable organosilicon compound, asilicone compound, and the like.

Examples of the insulating metal oxide include silica, alumina,zirconia, and the like. For example, the insulating metal oxide has aband-gap energy of 5.0 eV or more.

Examples of the ultraviolet ray screening agent having a benzotriazolestructure include 2-(2′-hydroxy-5′-methylphenyl)benzotriazole (“TinuvinP” available from BASF Japan Ltd.),2-(2′-hydroxy-3′,5′-di-t-butylphenyl)benzotriazole (“Tinuvin 320”available from BASF Japan Ltd.),2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (“Tinuvin326” available from BASF Japan Ltd.),2-(2′-hydroxy-3′,5′-di-amylphenyl)benzotriazole (“Tinuvin 328” availablefrom BASF Japan Ltd.), and the like. It is preferred that theultraviolet ray screening agent be an ultraviolet ray screening agenthaving a benzotriazole structure containing a halogen atom, and it ismore preferred that the ultraviolet ray screening agent be anultraviolet ray screening agent having a benzotriazole structurecontaining a chlorine atom, because those are excellent in ultravioletray screening performance.

Examples of the ultraviolet ray screening agent having a benzophenonestructure include octabenzone (“Chimassorb 81” available from BASF JapanLtd.), and the like.

Examples of the ultraviolet ray screening agent having a triazinestructure include “LA-F70” available from ADEKA CORPORATION,2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (“Tinuvin1577FF” available from BASF Japan Ltd.), and the like.

Examples of the ultraviolet ray screening agent having a malonic acidester structure include dimethyl 2-(p-methoxybenzylidene)malonate,tetraethyl-2,2-(1,4-phenylenedimethylidene)bismalonate,2-(p-methoxybenzylidene)-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)malonate,and the like.

Examples of a commercial product of the ultraviolet ray screening agenthaving a malonic acid ester structure include Hostavin B CAP, HostavinPR-25 and Hostavin PR-31 (any of these is available from Clariant JapanK.K.).

Examples of the ultraviolet ray screening agent having an oxanilidestructure include a kind of oxalic acid diamide having a substitutedaryl group and the like on the nitrogen atom such asN-(2-ethylphenyl)-N′-(2-ethoxy-5-t-butylphenyl)oxalic acid diamide,N-(2-ethylphenyl)-N′-(2-ethoxy-phenyl)oxalic acid diamide and2-ethyl-2′-ethoxy-oxanilide (“Sanduvor VSU” available from ClariantJapan K.K.).

Examples of the ultraviolet ray screening agent having a benzoatestructure include2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (“Tinuvin120” available from BASF Japan Ltd.), and the like.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the ultraviolet ray screening agent (a first layer, a secondlayer, or a third layer), the content of the ultraviolet ray screeningagent and the content of the benzotriazole compound are preferably 0.1%by weight or more, more preferably 0.2% by weight or more, furtherpreferably 0.3% by weight or more, especially preferably 0.5% by weightor more. In 100% by weight of the interlayer film or in 100% by weightof a layer containing the ultraviolet ray screening agent (a firstlayer, a second layer, or a third layer), the content of the ultravioletray screening agent and the content of the benzotriazole compound arepreferably 2.5% by weight or less, more preferably 2% by weight or less,further preferably 1% by weight or less, especially preferably 0.8% byweight or less. When the content of the ultraviolet ray screening agentis the above-described lower limit or more and the above-described upperlimit or less, deterioration in visible light transmittance after alapse of a period can be further suppressed. In particular, by settingthe content of the ultraviolet ray screening agent to be 0.2% by weightor more in 100% by weight of a layer containing the ultraviolet rayscreening agent, with regard to the interlayer film and laminated glass,the lowering in visible light transmittance thereof after the lapse of acertain period of time can be significantly suppressed.

(Oxidation Inhibitor)

It is preferred that the interlayer film contain an oxidation inhibitor.It is preferred that the first layer contain an oxidation inhibitor. Itis preferred that the second layer contain an oxidation inhibitor. It ispreferred that the third layer contain an oxidation inhibitor. One kindof the oxidation inhibitor may be used alone, and two or more kindsthereof may be used in combination.

Examples of the oxidation inhibitor include a phenol-based oxidationinhibitor, a sulfur-based oxidation inhibitor, a phosphorus-basedoxidation inhibitor, and the like. The phenol-based oxidation inhibitoris an oxidation inhibitor having a phenol skeleton. The sulfur-basedoxidation inhibitor is an oxidation inhibitor containing a sulfur atom.The phosphorus-based oxidation inhibitor is an oxidation inhibitorcontaining a phosphorus atom.

It is preferred that the oxidation inhibitor be a phenol-based oxidationinhibitor or a phosphorus-based oxidation inhibitor.

Examples of the phenol-based oxidation inhibitor include2,6-di-t-butyl-p-cresol (BHT), butyl hydroxyanisole (BHA),2,6-di-t-butyl-4-ethylphenol, stearylβ-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,2,2′-methylenebis-(4-methyl-6-butylphenol),2,2′-methylenebis-(4-ethyl-6-t-butylphenol),4,4′-butylidene-bis-(3-methyl-6-t-butylphenol),1,1,3-tris-(2-methyl-hydroxy-5-t-butylphenyl)butane,tetrakis[methylene-3-(3′,5′-butyl-4-hydroxyphenyl)propionate]methane,1,3,3-tris-(2-methyl-4-hydroxy-5-t-butylphenol)butane,1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,bis(3,3′-t-butylphenol)butyric acid glycol ester,bis(3-t-butyl-4-hydroxy-5-methylbenzenepropanoicacid)ethylenebis(oxyethylene), and the like. One kind or two or morekinds among these oxidation inhibitors are preferably used.

Examples of the phosphorus-based oxidation inhibitor include tridecylphosphite, tris(tridecyl) phosphite, triphenyl phosphite, trinonylphenylphosphite, bis(tridecyl)pentaerithritol diphosphite,bis(decyl)pentaerithritol diphosphite, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-tert-butyl-6-methylphenyl)ethyl ester phosphate,2,2′-methylenebis(4,6-di-t-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus,and the like. One kind or two or more kinds among these oxidationinhibitors are preferably used.

Examples of a commercial product of the oxidation inhibitor include“IRGANOX 245” available from BASF Japan Ltd., “IRGAFOS 168” availablefrom BASF Japan Ltd., “IRGAFOS 38” available from BASF Japan Ltd.,“Sumilizer BHT” available from Sumitomo Chemical Co., Ltd., “H-BHT”available from Sakai Chemical Industry Co., Ltd., “IRGANOX 1010”available from BASF Japan Ltd., and the like.

With regard to the interlayer film and laminated glass, in order tomaintain high visible light transmittance thereof over a long period oftime, the content of the oxidation inhibitor is preferably 0.03% byweight or more, more preferably 0.1% by weight or more in 100% by weightof the interlayer film or in 100% by weight of the layer containing theoxidation inhibitor (a first layer, a second layer, or a third layer).Moreover, since an effect commensurate with the addition of an oxidationinhibitor is not attained, it is preferred that the content of theoxidation inhibitor be 2% by weight or less in 100% by weight of theinterlayer film or in 100% by weight of the layer containing theoxidation inhibitor.

(Light Stabilizer)

It is preferred that the interlayer film contain a light stabilizer. Itis preferred that the first layer contain a light stabilizer. It ispreferred that the second layer contain a light stabilizer. It ispreferred that the third layer contain a light stabilizer. By using thelight stabilizer, discoloration is further suppressed and the visiblelight transmittance is less likely to lower even when the interlayerfilm is used over a long term or exposed to sunlight. One kind of thelight stabilizer may be used alone and two or more kinds thereof may beused in combination.

From the viewpoint of further suppressing the discoloration, it ispreferred that the light stabilizer be a hindered amine lightstabilizer.

Examples of the hindered amine light stabilizer include hindered aminelight stabilizers in which an alkyl group, an alkoxy group or a hydrogenatom is bonded to a nitrogen atom of the piperidine structure. From theviewpoint of further suppressing the discoloration, a hindered aminelight stabilizer in which an alkyl group or an alkoxy group is bonded toa nitrogen atom of the piperidine structure is preferred. The hinderedamine light stabilizer is preferably a hindered amine light stabilizerin which an alkyl group is bonded to a nitrogen atom of the piperidinestructure, and also preferably a hindered amine light stabilizer inwhich an alkoxy group is bonded to a nitrogen atom of the piperidinestructure.

As the hindered amine light stabilizer in which an alkyl group is bondedto a nitrogen atom of the piperidine structure, “Tinuvin765” and“Tinuvin622SF” available from BASF, and “ADK STAB LA-52” available fromADEKA, or the like can be recited.

As the hindered amine light stabilizer in which an alkoxy group isbonded to a nitrogen atom of the piperidine structure, “TinuvinXT-850FF”and “TinuvinXT-855FF” available from BASF, and “ADK STAB LA-81”available from ADEKA, or the like can be recited.

As the hindered amine light stabilizer in which a hydrogen atom isbonded to a nitrogen atom of the piperidine structure, “Tinuvin 770DF”available from BASF, and “Hostavin N24” available from Clariant, or thelike can be recited.

From the viewpoint of further suppressing the discoloration, the lightstabilizer has a molecular weight of preferably 2000 or less, morepreferably 1000 or less, further preferably 700 or less.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the light stabilizer (a first layer, a second layer, or athird layer), the content of the light stabilizer is preferably 0.0025%by weight or more, more preferably 0.025% by weight or more, and ispreferably 0.5% by weight or less, more preferably 0.3% by weight orless. When the content of the light stabilizer is the above lower limitor more and the above upper limit or less, discoloration is efficientlysuppressed.

(Other Ingredients)

Each of the interlayer film, the first layer, the second layer, and thethird layer may contain additives such as a coupling agent, a dispersingagent, a surfactant, a flame retardant, an antistatic agent, a pigment,a dye, an adhesive force regulator other than metal salt, amoisture-resistance agent, a fluorescent brightening agent, and aninfrared ray absorber, as necessary. One kind of these additives may beused alone, and two or more kinds thereof may be used in combination.

(Other Details of Interlayer Film)

The distance between one end and the other end of the interlayer film ispreferably 0.5 m or more, more preferably 0.8 m or more, and especiallypreferably 1 m or more, and is preferably 3 m or less, more preferably 2m or less, and especially preferably 1.5 m or less. When the interlayerfilm has a lengthwise direction and a widthwise direction, the distancebetween one end and the other end is the distance in the lengthwisedirection of the interlayer film. When the interlayer film has a squareplanar shape, the distance between one end and the other end is adistance between one end and the other end that are opposed to eachother.

From the viewpoint of further improving the sound insulating propertiesof laminated glass when the interlayer film has a two or more-layerstructure or a three or more-layer structure, the glass transitiontemperature of the first layer is preferably 30° C. or less, morepreferably 20° C. or less, further preferably 10° C. or less. The glasstransition temperature of the first layer is preferably −15° C. or more.

The thickness of the interlayer film is not particularly limited. Fromthe viewpoint of the practical aspect and the viewpoint of sufficientlyenhancing the heat shielding property, the thickness of the interlayerfilm is preferably 0.1 mm or more, and more preferably 0.25 mm or moreand is preferably 3 mm or less, and more preferably 1.5 mm or less. Whenthe thickness of the interlayer film is the above-described lower limitor more, the penetration resistance of laminated glass is enhanced. Whenthe thickness of the interlayer film is the above upper limit or less,the transparency of the interlayer film is further improved.

The thickness of the interlayer film is designated as T. From theviewpoint of making discoloration more difficult to occur in an end partof laminated glass, and further suppressing deterioration intransparency of laminated glass in the case of a multi-layeredinterlayer film, the thickness of the first layer is preferably 0.0625 Tor more, more preferably 0.1 T or more, and is preferably 0.375 T orless, and more preferably 0.25 T or less.

From the viewpoint of making discoloration more difficult to occur in anend part of laminated glass, and further suppressing deterioration intransparency of laminated glass, the thickness of the second layer ispreferably 0.625 T or more, more preferably 0.75 T or more, and ispreferably 0.9375 T or less, and more preferably 0.9 T or less. When thethickness of the second layer is the above-described lower limit or moreand the above-described upper limit or less, bleeding out of theplasticizer can be suppressed.

From the viewpoint of making discoloration more difficult to occur in anend part of laminated glass, a total thickness of the second layer andthe third layer is preferably 0.625 T or more, more preferably 0.75 T ormore, and is preferably 0.9375 T or less, and more preferably 0.9 T orless when the interlayer film includes the second layer and the thirdlayer. When the total thickness of the second layer and the third layeris the above-described lower limit or more and the above-described upperlimit or less, bleeding out of the plasticizer can be suppressed.

The interlayer film may be an interlayer film having a uniformthickness, or may be an interlayer film having varying thickness. Thesectional shape of the interlayer film may be a rectangular shape andmay be a wedge-like shape.

The method for producing the interlayer film is not particularlylimited. In the case of a single-layered interlayer film, examples ofthe production method of the interlayer film include a method ofextruding a resin composition with an extruder. In the case of amulti-layered interlayer film, examples of the production method of theinterlayer film include a method of separately forming respective resincompositions used for constituting respective layers into respectivelayers, and then layering the respective obtained layers, a method ofcoextruding respective resin compositions used for constitutingrespective layers with an extruder and layering the respective layers,and the like. A production method of extrusion-molding is preferredbecause the method is suitable for continuous production.

For the reason of excellent production efficiency of the interlayerfilm, it is preferred that the second layer and the third layer containthe same polyvinyl acetal resin. For the reason of excellent productionefficiency of the interlayer film, it is preferred that the second layerand the third layer contain the same polyvinyl acetal resin and the sameplasticizer. For the reason of excellent production efficiency of theinterlayer film, it is further preferred that the second layer and thethird layer be formed of the same resin composition.

It is preferred that the interlayer film have a concave-convex shape inat least one surface of the surfaces of both sides. It is more preferredthat the interlayer film have protrusions and recesses on surfaces ofboth sides. Examples of the method for forming the protrusions andrecesses include, but are not particularly limited to, a lip embossmethod, an emboss roll method, a calender roll method, and a profileextrusion method. The emboss roll method is preferred because a largenumber of embosses of the concave-convex shape, which is aquantitatively constant concave-convex pattern, can be formed.

(Other Details of Laminated Glass)

Examples of the lamination glass member include a glass plate, a PET(polyethylene terephthalate) film, and the like. As the laminated glass,laminated glass in which an interlayer film is sandwiched between aglass plate and a PET film or the like, as well as laminated glass inwhich an interlayer film is sandwiched between two glass plates, isincluded. The laminated glass is a laminate including a glass plate, andit is preferred that at least one glass plate be used. It is preferredthat each of the first lamination glass member and the second laminationglass member be a glass plate or a PET film and at least one of thefirst lamination glass member and the second lamination glass member bea glass plate.

Examples of the glass plate include a sheet of inorganic glass and asheet of organic glass. Examples of the inorganic glass include floatplate glass, heat ray-absorbing plate glass, heat ray-reflecting plateglass, polished plate glass, figured glass, wired plate glass, and thelike. The organic glass is synthetic resin glass substituted forinorganic glass. Examples of the organic glass include a polycarbonateplate, a poly(meth)acrylic resin plate, and the like. Examples of thepoly(meth)acrylic resin plate include a polymethyl (meth)acrylate plate,and the like.

The thickness of the lamination glass member is preferably 1 mm or more,and is preferably 5 mm or less, more preferably 3 mm or less. Moreover,when the lamination glass member is a glass plate, the thickness of theglass plate is preferably 1 mm or more, and is preferably 5 mm or less,more preferably 3 mm or less. When the lamination glass member is a PETfilm, the thickness of the PET film is preferably 0.03 mm or more and ispreferably 0.5 mm or less.

The method for producing the laminated glass is not particularlylimited. First, the interlayer film is sandwiched between the firstlamination glass member and the second lamination glass member to obtaina laminate. Then, for example, by passing the obtained laminate throughpressure rolls or subjecting the obtained laminate to decompressionsuction in a rubber bag, the air remaining between the first and thesecond lamination glass members and the interlayer film is removed.Then, the laminate is preliminarily bonded together at about 70 to 110°C. to obtain a preliminarily press-bonded laminate. Next, by putting thepreliminarily press-bonded laminate into an autoclave or by pressing thelaminate, the laminate is press-bonded at about 120 to 150° C. and undera pressure of 1 to 1.5 MPa. In this way, laminated glass can beobtained. At the time of producing the laminated glass, a first layer, asecond layer, and a third layer may be layered.

Each of the interlayer film and the laminated glass can be used forautomobiles, railway vehicles, aircraft, ships, buildings, and the like.Each of the interlayer film and the laminated glass can also be used forapplications other than these applications. It is preferred that theinterlayer film and the laminated glass be an interlayer film andlaminated glass for vehicles or for building respectively, and it ismore preferred that the interlayer film and the laminated glass be aninterlayer film and laminated glass for vehicles respectively. Each ofthe interlayer film and the laminated glass can be used for awindshield, side glass, rear glass, roof glass or glass for backlight ofan automobile, and the like. The interlayer film and the laminated glassare suitably used for automobiles. The interlayer film is used forobtaining laminated glass of an automobile.

In the present invention, since it is possible to prevent occurrence ofdiscoloration in an end part of laminated glass, and it is possible tokeep the appearance of laminated glass excellent, the laminated glass isused as side glass in automobiles, roof glass or glass for backlight inan automobile. The side glass is easy to visually recognize. The qualityof the roof glass is easily altered by the sunlight or the like.Regarding the glass for backlight, a defect in appearance is easilyrecognized by backlight. By using the laminated glass according to thepresent invention as side glass, roof glass or glass for backlight, itis possible to achieve excellent appearance and suppress the alternationin quality. The laminated glass is laminated glass that is to be used asglass for windshield in an automobile, and it is preferred that blackcoating be not applied on a contact surface between the interlayer filmand a lamination glass member on an outer side of the automobile.

Hereinafter, the present invention will be described in more detail withreference to examples and comparative examples. The present invention isnot limited only to these examples.

With regard to the polyvinyl butyral resin (PVB) used in the followingexamples and comparative examples, the butyralization degree (theacetalization degree), the acetylation degree and the content of thehydroxyl group were measured by a method in accordance with JIS K6728“Testing methods for polyvinyl butyral”. In this connection, even in thecases of being measured according to ASTM D1396-92, numerical valuessimilar to those obtained by a method in accordance with JIS K6728“Testing methods for polyvinyl butyral” were exhibited.

(Polyvinyl Acetal Resin (1))

Polyvinyl butyral resin having a butyralization degree of 68% by mole,an acetylation degree of 1% by mole, a content of the hydroxyl group of31% by mole, and a weight average molecular weight of 150,000

(Polyvinyl Acetal Resin (X))

Polyvinyl butyral resin having a butyralization degree of 68% by mole,an acetylation degree of 1%, a content of the hydroxyl group of 31% bymole, and a weight average molecular weight of 68,000

Comparative Example 1

Preparation of Composition for Forming Interlayer Film:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming an interlayer film.

100 parts by weight of Polyvinyl acetal resin (1)

40 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) whichis a plasticizer

An amount that is 0.2 parts by weight in the obtained interlayer film ofan ultraviolet ray screening agent(2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole)

An amount that is 0.2% by weight in the obtained interlayer film of anoxidation inhibitor (2,6-di-t-butyl-p-cresol)

Preparation of Interlayer Film:

By extruding a composition for forming an interlayer film with anextruder, a single-layered interlayer film (thickness: 800 μm) wasprepared.

Preparation of Laminated Glass:

The obtained interlayer film was cut out into a piece of 8 cm long×8 cmwide. Then the interlayer film was sandwiched between two sheets ofclear glass (8 cm long×8 cm wide×2.5 mm thick), and vacuum-pressed byretention at 90° C. for 30 minutes with a vacuum laminator, to obtain alaminate. In the laminate, the part of the interlayer film protrudingfrom the clear glass was cut off, to obtain laminated glass.

Example 1

Example of Interlayer Film in which End Part is Impregnated with AlkaliLiquid:

An alkali liquid containing an alkali component in a mixture ofisopropanol and methanol was prepared.

An end part of the laminated glass obtained in Comparative Example 1 wasdipped in the alkali liquid, and the end part of the interlayer film wasimpregnated with the alkali liquid, and thus laminated glass wasobtained.

Example 2

Example of Interlayer Film in which End Part is Subjected to SilicaSputtering:

End parts of the laminated glass of Comparative Example 1 were subjectedto silica sputtering to obtain laminated glass.

Example 3

Example of Interlayer Film in which End Part is Subjected to MetalSputtering:

End parts of the laminated glass of Comparative Example 1 were subjectedto metal sputtering to obtain laminated glass.

Example 4

Example of Interlayer Film in which Polyvinyl Acetal Resin Sheet is Usedin End Part:

A polyvinyl acetal resin sheet was pasted to an end part of thelaminated glass of Comparative Example 1 to obtain laminated glass.

Example 5

Example of Interlayer Film in which Light Stabilizer-Containing Sheet isUsed in End Part:

A light stabilizer-containing sheet (light stabilizer (“Tinuvin765”available from BASF) was pasted to an end part of the laminated glass ofComparative Example 1 to obtain laminated glass.

Example 6

Example of Interlayer Film in which End Part is Impregnated with LightStabilizer:

End parts of the laminated glass of Comparative Example 1 wereimpregnated with a light stabilizer: “Tinuvin765” available from BASF toobtain laminated glass.

Example 7

Example of Interlayer Film in which Sealing Sheet is Used in End Part:

A sealing sheet was pasted to an end part of the laminated glass ofComparative Example 1 to obtain laminated glass. The sealing sheet hashigh airtightness. The sealing sheet prevents, for example, leakage ofan oxidation inhibitor.

Comparative Example 2

Preparation of Composition for Forming First Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a first layer.

100 parts by weight of Polyvinyl acetal resin (X)

60 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) whichis a plasticizer

An amount that is 0.2 parts by weight in the obtained interlayer film ofan ultraviolet ray screening agent(2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole)

An amount that is 0.2% by weight in the obtained interlayer film of anoxidation inhibitor (2,6-di-t-butyl-p-cresol)

Preparation of Composition for Forming Second Layer and Third Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a composition forforming a second layer and a third layer.

100 parts by weight of Polyvinyl acetal resin (1)

40 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) whichis a plasticizer

An amount that is 0.2 parts by weight in the obtained interlayer film ofan ultraviolet ray screening agent(2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole)

An amount that is 0.2% by weight in the obtained interlayer film of anoxidation inhibitor (2,6-di-t-butyl-p-cresol)

Preparation of Interlayer Film:

The composition for forming the first layer, and the composition forforming the second layer and the third layer were coextruded by using aco-extruder. An interlayer film (760 μm thick) having a laminatestructure of the second layer (330 μm thick)/the first layer (100 μmthick)/the third layer (330 μm thick) was prepared.

Preparation of Laminated Glass:

The obtained interlayer film was cut out into a piece of 8 cm long×8 cmwide. Then the interlayer film was sandwiched between two sheets ofclear glass (8 cm long×8 cm wide×2.5 mm thick), and vacuum-pressed byretention at 90° C. for 30 minutes with a vacuum laminator, to obtain alaminate. In the laminate, the part of the interlayer film protrudingfrom the clear glass was cut off, to obtain laminated glass.

Example 8

Example of Interlayer Film in which End Part is Impregnated with AlkaliLiquid:

An alkali liquid containing an alkali component in a mixture ofisopropanol and methanol was prepared.

An end part of the laminated glass obtained in Comparative Example 2 wasdipped in the alkali liquid, and the end part of the interlayer film wasimpregnated with the alkali liquid, and thus laminated glass wasobtained.

Example 9

Example of Interlayer Film in which End Part is Subjected to SilicaSputtering:

An end part of the laminated glass of Comparative Example 2 wassubjected to silica sputtering to obtain laminated glass.

Example 10

Example of Interlayer Film in which End Part is Subjected to MetalSputtering:

An end part of the laminated glass of Comparative Example 2 wassubjected to metal sputtering to obtain laminated glass.

Example 11

Example of Interlayer Film in which a Polyvinyl Acetal Resin Sheet isUsed in End Part:

A polyvinyl acetal resin sheet was pasted to an end part of thelaminated glass of Comparative Example 2 to obtain laminated glass.

Example 12

Example of Interlayer Film in which Light Stabilizer-Containing Sheet isUsed in End Part:

A light stabilizer-containing sheet (light stabilizer: “Tinuvin765”available from BASF) was pasted to an end part of the laminated glass ofComparative Example 2 to obtain laminated glass.

Example 13

Example of Interlayer Film in which End Part is Impregnated with LightStabilizer:

An end part of the laminated glass of Comparative Example 2 wasimpregnated with a light stabilizer: “Tinuvin765” available from BASF toobtain laminated glass.

Example 14

Example of Interlayer Film in which Sealing Sheet is Used in End Part:

A sealing sheet was pasted to an end part of the laminated glass ofComparative Example 2 to obtain laminated glass. The sealing sheet hashigh airtightness. The sealing sheet prevents, for example, leakage ofan oxidation inhibitor.

(Evaluation)

(1) Preparation of Laminated Glass after Light Irradiation Test

The light irradiation test was conducted using SX-75 available from SugaTest Instruments Co., Ltd. The obtained laminated glass (laminated glassbefore light irradiation test) was fixed to a sample fixing tool so thatone end part of the laminated glass was exposed. From one side of thesurface of the fixed laminated glass, xenon light 180 W/m² with anirradiance of 180 W/m² (irradiance measuring wavelength 300 to 400 nm)was applied at a black panel temperature of 83° C., a temperature insidethe vessel of 50° C. and a humidity of 50% RH for 2000 hours. Thelaminated glass after light irradiation test was obtained.

(2) Content of Hydroxyl Group and Acetalization Degree

Laminated glass after the light irradiation test obtained in the above(1) was prepared.

A content of the hydroxyl group of polyvinyl acetal resin in the layer(the first layer, or the second and the third layers) of the interlayerfilm being in contact with the clear glass at a position of 2 mminwardly in the direction orthogonal to an end side having an end partfrom the end part of the laminated glass after the light irradiationtest was measured. Also, a content of the hydroxyl group of polyvinylacetal resin in the layer (the first layer, or the second and the thirdlayers) of the interlayer film being in contact with the clear glass ata position of 70 mm inwardly in the direction orthogonal to an end sidehaving an end part from the end part of the laminated glass after thelight irradiation test was measured. A ratio (content of hydroxyl groupat position of 2 mm/content of hydroxyl group at position of 70 mm) wasdetermined. Also the acetalization degree of the polyvinyl acetal resinwas evaluated in the same manner.

(3) Condition of Discoloration in Interlayer Film in End Part ofLaminated Glass after Light Irradiation Test

Laminated glass after the light irradiation test obtained in the above(1) was prepared.

After the light irradiation test, the end part of the laminated glasswas observed, and the condition of discoloration in the end part of thelaminated glass was evaluated. The condition of discoloration was judgedaccording to the following criteria.

[Criteria for Condition of Discoloration]

∘: No discoloration occurs in interlayer film in end part of laminatedglass, or discoloration occurs within length of 1 mm or less inwardlyfrom end part in interlayer film in end part of laminated glass (lengthin which discoloration occurs is 1 mm or less).

x: Discoloration occurs in length of more than 1 mm inwardly from endpart in interlayer film in end part of laminated glass (length in whichdiscoloration occurs is more than 1 mm).

The details and the results are shown in the following Tables 1, 2.

TABLE 1 Comparative Example 1 Example 2 Example 3 Example 4 Example 5Example 6 Example 7 Example 1 Configuration Difference from ImpregnationSilica Metal Use of Use of light Impregnation Use of — of interlayerComparative with alkali sputtering sputtering polyvinyl stabilizer- withlight sealing film Example 1 liquid acetal resin containing stabilizersheet sheet sheet Content of hydroxyl group at 32.0 31.0 31.0 32.0 31.031.0 31.0 34.0 position of 2 mm (% by mole) Content of hydroxyl group at30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 position of 70 mm (% by mole)Ratio (content of hydroxyl 1.07 1.03 1.03 1.07 1.03 1.03 1.03 1.13 groupat position of 2 mm/ content of hydroxyl group at position of 70 mm)Ratio (acetalization degree at 0.971 0.986 0.986 0.971 0.986 0.986 0.9860.942 position of 2 mm/ acetalization degree at position of 70 mm)Condition of discoloration in ∘ ∘ ∘ ∘ ∘ ∘ ∘ x interlayer film in endpart of laminated glass

TABLE 2 Comparative Example 8 Example 9 Example 10 Example 11 Example 12Example 13 Example 14 Example 2 Configuration Difference fromImpregnation Silica Metal Use of Use of light Impregnation Use of — ofinterlayer Comparative with alkali sputtering sputtering polyvinylstabilizer- with light sealing film Example 2 liquid acetal resincontaining stabilizer sheet sheet sheet Content of hydroxyl group at32.0 31.0 31.0 32.0 31.0 31.0 31.0 34.0 position of 2 mm (% by mole)Content of hydroxyl group at 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0position of 70 mm (% by mole) Ratio (content of hydroxyl 1.07 1.03 1.031.07 1.03 1.03 1.03 1.13 group at position of 2 mm/ content of hydroxylgroup at position of 70 mm) Ratio (acetalization degree at 0.971 0.9860.986 0.971 0.986 0.986 0.986 0.942 position of 2 mm/ acetalizationdegree at position of 70 mm) Condition of discoloration in ∘ ∘ ∘ ∘ ∘ ∘ ∘x interlayer film in end part of laminated glass

EXPLANATION OF SYMBOLS

-   -   1: Interlayer film    -   1 a: First surface    -   1 b: Second surface    -   2: First layer    -   2 a: First surface    -   2 b: Second surface    -   3: Second layer    -   3 a: Outer surface    -   4: Third layer    -   4 a: Outer surface    -   11: Laminated glass    -   21: First lamination glass member    -   22: Second lamination glass member    -   31: Interlayer film    -   31 a: First surface    -   31 b: Second surface    -   41: Laminated glass

The invention claimed is:
 1. A laminated glass comprising a firstlamination glass member, a second lamination glass member, and aninterlayer film containing a thermoplastic resin, the interlayer filmbeing arranged between the first lamination glass member and the secondlamination glass member, wherein, the thermoplastic resin includes apolyvinyl acetal resin, wherein when the laminated glass is subjected toa light irradiation test, no discoloration occurs in the interlayer filmirradiated with light in an end part of the laminated glass, or anydiscoloration that occurs is within a length of 1 mm or less inwardlyfrom the end part of the interlayer film in the end part of thelaminated glass, and wherein, when the laminated glass is subjected tothe light irradiation test, a ratio of a content of the hydroxyl groupof the polyvinyl acetal resin in a layer of the interlayer film incontact with the lamination glass member at a position of 2 mm inwardlyfrom an end part of the laminated glass to a content of the hydroxylgroup of the polyvinyl acetal resin in a layer in the interlayer film incontact with the lamination glass member at a position of 70 mm inwardlyfrom an end part of the laminated glass is 1.03 or more and 1.2 or less,the light irradiation test comprising: irradiating the laminated glasswith xenon light at a black panel temperature of 83° C., a temperatureinside the vessel of 50° C. and a humidity of 50% RH for 2000 hours, thexenon light being irradiated from the first lamination glass member sidewhen the first lamination glass member and the second lamination glassmember have the same visible light transmittance, and the xenon lightbeing irradiated from the side of the lamination glass member having ahigher visible light transmittance when the first lamination glassmember and the second lamination glass member are different in visiblelight transmittance, wherein the irradiance at the time of irradiationwith xenon light is 180 W/m², the wavelength for measuring irradiance is300 to 400 nm, an inner filter is made of quartz, and an outer filter ismade of quartz: #275 (cutoff 275 nm).
 2. The laminated glass accordingto claim 1, wherein a content of the hydroxyl group of the polyvinylacetal resin in the layer of the interlayer film in contact with thelamination glass member at a position of 2 mm inwardly from an end partof the laminated glass after the light irradiation test is 30% by moleor less.
 3. The laminated glass according to claim 1, wherein thepolyvinyl acetal resin is a polyvinyl butyral resin.
 4. The laminatedglass according to claim 1, wherein there is a portion in which alateral surface of the interlayer film is exposed in an end part of thelaminated glass.
 5. The laminated glass according to claim 1, whereinthe interlayer film has a layer having a glass transition temperature of10° C. or less and containing a thermoplastic resin, or a layer that iscolored and contains a thermoplastic resin.
 6. The laminated glassaccording to claim 1, wherein the interlayer film includes a first layercontaining a thermoplastic resin, and a second layer containing athermoplastic resin, and the second layer is arranged on a first surfaceside of the first layer.
 7. The laminated glass according to claim 6,wherein the interlayer film includes a third layer containing athermoplastic resin, and the third layer is arranged on a second surfaceside opposite to the first surface side of the first layer.
 8. Thelaminated glass according to claim 1, wherein the interlayer film has avisible light transmittance of 70% or more.
 9. The laminated glassaccording to claim 1, to be used as glass for windshield in anautomobile, wherein black coating is not applied on a contact surfacebetween the interlayer film and a lamination glass member on an outerside of the automobile.
 10. The laminated glass according to claim 1, tobe used as side glass, roof glass or glass for backlight in automobiles.